The frequency of oscillation of typical voltage controlled oscillators is determined by the capacitance value of a varactor in a resonant stage in the oscillator. The value of the varactor capacitance is a function of the magnitude of a control voltage applied to the varactor. See, for example, U.S. Pat. Nos. 4,853,655, 4,887,053, and 4,973,922. The relationship between control voltage and varactor capacitance, and, therefore, the relationship between the control voltage and the frequency of oscillation, is not always desirable. For example, it is frequently desirable that the frequency of oscillation be a linear function of control voltage magnitude. Due to nonlinearities in the varactor--for example, nonlinearities at low signal levels--the oscillation frequency is not a linear function of control voltage magnitude. Many attempts have been made to satisfactorily linearize oscillation frequency vs control voltage magnitude. Techniques to provide a more linear transfer function between the control voltage and the output frequency include the use of external coils and restriction of the voltage range to linear regions of the varactor capacitance characteristic. These techniques increase manufacturing costs and reduce the range over which frequency may be controlled. In addition, these techniques are not easily implemented on a single integrated circuit.